/Engine/Source/Runtime/SlateCore/Public/Animation/CurveSequence.h
Plays forward if it can, otherwise holds it at the end of the animation, if we play in reverse it will reverse the animation if it can
void PlayRelative ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & InOwnerWidget, bool bForward )